WASHINGTON — President Donald Trump fired six National Security Council officials after an extraordinary meeting in the Oval Office with far-right activist Laura Loomer, who laid out a list of people she believed were disloyal to the president, according to a U.S. official with direct knowledge of the matter.

The six officials were among those vilified by Loomer during the meeting Wednesday, the official said. Loomer walked into the White House with a sheaf of papers, which amounted to a mass of opposition research attacking the character and loyalty of numerous NSC officials. She proceeded to excoriate them in front of Michael Waltz, the national security adviser, who was also in the meeting.

It was a remarkable spectacle: Loomer, a Sept. 11 conspiracy theorist who is viewed as extreme even by some of Trump’s far-right allies, apparently wielding more influence over the staff of the National Security Council than Waltz, who runs the agency.

Waltz was not among those who were fired; nor was one of Loomer’s top targets, the deputy national security adviser Alex Wong, the U.S. official said. Apart from the firings, several other officials who had been detailed to the council were reassigned back to their home agencies over the weekend, even before the White House meeting. The account of the White House meeting and the subsequent firings is based on interviews with eight people with knowledge of the events. They asked for anonymity to discuss confidential meetings and discussions.

Loomer has been part of a group effort by some Trump allies to disparage members of the president’s White House staff whom they consider too hawkish, too eager to commit U.S. troops around the world and fundamentally at odds with Trump’s “America First” foreign policy.

The agitators have used the phrase “neocon” — short for neoconservative — to describe many of those staff members working for Waltz.

The roughly 30-minute meeting with Loomer was also attended by Vice President JD Vance and other senior officials, including the chief of staff, Susie Wiles; the head of the personnel office, Sergio Gor; and Commerce Secretary Howard Lutnick.